from the Colchester Chalk. 241 



ensis, M. elongata, M. trilohata, Frondicularia Vemeuiliana, F. 

 Archiaciana, Flabellina ruyosa, F. cordata, Cristellaria rotulata, 

 Rosalina ammanoides, R. marginata, Truncatulina Beaumontiana, 

 Globigerina cretacea, and Bulimina variabilis are the most nume- 

 rous. Cristellaria rotulata is especially conspicuous in the group, 

 and is a species that abounds in the chalk* of every locality, 

 both in England and on the continent. Some of these forms 

 have been selected for illustration in Plate IX. The recent ana- 

 logues of these fossil Microzoa are exceedingly plentiful in most 

 seas and estuaries, their elegant little shells being easily obtained 

 in the sands, mud, and seaweeds. The Foraminiferae hold but a 

 low place in the scale of animal life, and are not far removed 

 from the Sponges. They are stomachless, and consist of a 

 number of minute gelatinous bodies (in shape globular, disci- 

 form, wedgelike, &c.), arranged in a more or less regular, often 

 symmetrical series (straight, curved, spiral, alternate, &c,), and 

 coated with a thin calcareous shell, which is often perforated all 

 over, and always exhibits one or more large holes, through 

 which the gelatinous mass is protruded for the formation of a 

 new bud-like body, and in some cases in the form of irregular 

 tentacles (pseudopodia) for the purposes of attachment and loco- 

 motion. Certain species are characteristic of diflFerent oceanic 

 areas in the present day ; and the different geologic epochs have 

 their own peculiar forms. Exceptions to this rule exist ; some 

 species have a world-wide existence, and some species of the 

 genera Globigerina, Dentalina, Globulina, &c. have extended their 

 range from the chalk and tertiary seas to the present. 



Of the remains of Bryozoa, — which are minute animals, allied 

 to Mollusca, inhabiting cellular cavities on small calcareous axes, 

 which are generally cylindrical or flattened, and form branched 

 or foliaceous bodies, either free or fixed to rocks, shells, seaweeds, 

 &c., — numerous fragmentary remains were obtained from the 

 chalk of Colchester. Owing, however, to the fragments having 

 been already much water-worn previously to their having been 

 imbedded in the chalky mud of the ancient sea, but little definite 

 indication of the original shape of the characteristic cell-cavities 

 remains, the delicate cell-mouths and their tracery having been 

 quite worn away. A few specimens illustrative of these forms 

 are shown in Plate VIII. 



The Entomostraca are small bivalved Crustaceans : the valves 

 are generally of an oblong or oval shape, and are distinguished 

 one from another chiefly by the character of the hingement. 



* It is also abundant in the sands of the shore at Dover (from the dis- 

 integrated chalk of the cliflFs), in the drift of Essex, &c., and the chalk 

 detritus of Charing, Kent. 



Ann. i^ Mag. N. Hist. Ser. 2. To/.xii. 17 



